I.N. 31 LIVING THINGS: Properties of Water AndAcids/BasesHeadingsVocabulary Important Words

Living Things Use & Need Energy a.) Energy comes from food, used to maintain body b.) AUTOTROPH: produce own food c.) HETEROTROPH: must consume food d.) DECOMPOSER: breaks down dead material for food

Living things respond to their surrounding stimulus a.) Rxn to a stimulus Action b.) Action causes a rxn Response c.) Rxn is called a: Response one d.) Involves one individual

Question: Describe the properties of water that make it important to living things. Water is Polar: It has an uneven distribution of electrons between the hydrogen and oxygen atoms It has an uneven distribution of electrons between the hydrogen and oxygen atoms One side is positive One side is positive Other is negative Other is negative

Water Properties: Water is cohesive  Cohesion  Cohesion: same  attraction B/T same molecules  causes molecules to draw inward at surface  Ex: Some insects & spiders can “walk” on the surface of H2O Water is adhesive  Adhesion  Adhesion: different  attraction between different mol. H20 to bend  causes H20 to bend at surface  Ex: capillary action-pulls column of water up to the top of a plant

 Water is called “Universal solvent”: polarity  Water is called “Universal solvent”: dissolves many other substances due to polarity  Differences in charges pulls/pushes substances apart Water exhibits evaporative cooling  Water exhibits evaporative cooling: removes heat when it evaporates from a surface  Ex: sweating cools skin Water expands during freezing  Water expands during freezing: expands into crystal formation releasing heat  Ex: rocks broken up by ice creating soil; ice layer protects fruit from freezing

Acids, Bases and the pH scale pH scale how acidic something is  The pH scale measures the concentration of H+ ions (how acidic something is)  Ranges from 0-14  At 7: neutral  At 7: H+ ions and OH- ions are equal so it is neutral  0-7: Acidic  0-7: Acidic, has more H+ ions  7-14: Basic  7-14: Basic, has more OH- ions

ACIDS:release H+ ACIDS: release H+ when mixed with water  Sour, corrosive  Ex: HCl, H 2 SO 4 H at front  Always have H at front of formula BASES: release OH- BASES: release OH- when mixed with water  Bitter, slippery, usually in cleaners  NaOH, CaOH OH at end  Always have OH at end of formula

What is a buffer? weak acids or basesreact strong acids and bases  Buffers are weak acids or bases that react w/strong acids and bases  prevent sharp changes in pH neutralize pH  Helps to neutralize pH Homeostasis  Helps control pH in blood, digestive tract, etc. = maintain Homeostasis